Irrigating a 20-Foot Slope with 54 PSI: Lower Flow Rate to Save Pressure

Pressure Budget for Sloped Yard: You're 2 PSI Short at 10 GPM

54 PSI static. Losses: Backflow (8), elevation (20 ft × 0.433 = 9), pipe (175 ft), valve, rotor min (25). Total > 54.

Fixed Losses You Can't Change

• Elevation: 9 PSI
• Backflow: 8 PSI

Adjustable: Flow Rate

• At 10 GPM: 1" valve loss ~3 PSI, 1" pipe loss ~2 PSI/100 ft = 3.5 PSI.
• Remaining: 54 – 9 – 8 – 3 – 3.5 = 30.5 PSI at head (above 25 min).

Design Change

Split the slope into two zones at 5–6 GPM each. Adds a valve but keeps pressure adequate. Cheaper than booster pump or larger pipe.

Key Insight

Lower flow = lower friction loss = more pressure at head. Match nozzle GPM to available pressure.